Organic thin film transistor with ion exchanged glass substrate

ABSTRACT

Articles utilizing strengthened glass substrates, for example, ion-exchanged glass substrates, in combination with organic molecules or polymers are described along with methods for making the articles. The articles are useful in electronics-based devices that utilize organic thin film transistors.

This application claims the benefit of priority under 35 USC §119 ofU.S. Provisional Application Ser. No. 61/567,342 filed Dec. 6, 2011 thecontent of which is relied upon and incorporated herein by reference inits entirety.

FIELD

Embodiments generally relate to articles using strengthened glass as asubstrate and more particularly to using strengthened glass incombination with organic molecules or polymers as a substrate forelectronics devices, such as thin film transistors, and methods formaking the articles.

TECHNICAL BACKGROUND

As portable electronics devices, such as e-readers, video displays, andother gadgetry continue to gain worldwide acceptance, the demand forimproved mechanical durability in these devices grows. Many of thesedevices contain thin film transistors, most often comprising glasssupport substrates. For those products using glass as the backplanesubstrate, an impact with the floor, harsh environmental conditions, orsimilar event could cause device failure. For example, fracturing of theglass backplane substrate is a dominant failure mode in currente-readers.

Glass is viewed by device manufacturers as limiting the devicedurability, and attempts have been made to replace it with othermaterials such as metal sheets (e.g. aluminum or stainless steel) andpolymer films (polyethylene terephthalate or polyethylene naphthalate).Although metal and polymer films are non-brittle, these materials alsohave limitations. Metal films are often too rough and require aplanarization layer and polymer films are prone to solventincompatibility and have thermal-dimensional limitations. Additionally,metal and polymer substrates may provide additional compatibility issuesnot present with glass when used as a support substrate.

The ideal substrate would be able to withstand increased temperatures,provide a surface with low roughness, be unaffected by processingsolvents, and be able to withstand everyday final product-type abuse.Current substrates fail to meet at least one of these important factors,leading to an unmet need to find novel substrates that have improvedperformance.

SUMMARY

Fabrication of active electronic structures on ion-exchanged glass willenable strong, nearly unbreakable glass to be used as the electronicbackplane in electronic devices such as liquid crystal displays. If theelectronic backplanes were composed of ion-exchanged glass, much of thisextra hardware could be eliminated, and new, frameless devices could bedeveloped, with potential for greatly improved aesthetics, lighterweight, lower manufacturing costs, and/or improved product durability.If the active electronics on ion-exchanged glass are also composed ofoptically transparent materials, then this would enable transparent,all-glass electronic devices.

One possibility is to use strengthened glass, such as Gorilla®(registered Trademark of Corning Incorporated) Glass as the backplanesubstrate. Ion-exchanged Gorilla® Glass, however, is sodium andpotassium rich on the surface and alkali metal is a disadvantage insemiconductor device operation and fabrication, for example, TFTmanufacturing. Free alkali metal ions can contaminate typical TFTdevices, such as silicon (Si) TFTs, and alkali containing glass is to beavoided in the typical high temperature vacuum processing steps used tomake inorganic TFTs may allow transfer of alkali metal ions into theactive semi-conductor, which is detrimental to performance.Traditionally, alkali-free glass has been used in TFTs as it will notcontaminate the silicon, but alkali-free glass does not have themechanical reliability of ion-exchanged glass.

Another possibility is the use of more traditional glasses that arethermally or chemically hardened, such as soda-lime glass that has beentempered. However, soda-lime glasses have high levels of alkali metalsas well and therefore use of these materials may also result incontamination of TFT devices.

It has now unexpectedly been discovered that semiconductor devices, forexample, organic TFTs can be directly fabricated onto a mechanicallydurable strengthened glass, for example, an ion-exchanged substrate,with no barrier layer present. Embodiments described herein may provideone or more of the following advantages: provide a practical way tofabricate organic TFTs and circuits on strengthened glass, includingion-exchanged and tempered glass substrates; provide a means of usingstrengthened glass, for example, ion-exchanged or tempered glass assuitable substrates for display backplanes; allow the fabrication ofelectronic devices on strengthened glass, for example, ion-exchanged ortempered glasses without changing the superior compression strength ofthe glass; and/or provide an improved method with decreased cost sincethe removal of the barrier layer allows for a thinner device with lessproduction steps.

A first embodiment comprises an article comprising: a strengthened glasssubstrate having a first surface and a second surface and having aVickers crack initiation threshold of at least 7 kgf; an organicsemiconductor layer having a first surface and a second surface; adielectric layer having a first surface and a second surface; and atleast one electrode; wherein the article does not contain a barrierlayer. In some embodiments, the at least one electrode comprises a gateelectrode, a drain electrode, and a source electrode. In someembodiments, the at least one electrode comprises a metal, conductingmetal oxide film, conducting metal nanoparticulate ink, or conductivepolymer. In some embodiments, the organic semiconductor layer comprisesa semiconducting small molecule, semiconducting oligomer, orsemiconducting polymer. In some embodiments, the dielectric layercomprises an organic or inorganic material that may be applied as a filmat a temperature less than about 250° C. In some embodiments, thestrengthened glass comprises an ion-exchanged glass. In someembodiments, the strengthened glass comprises tempered glass. In someembodiments, the glass is an aluminoborosilicate,alkalialuminoborosilicate, aluminosilicate, alkalialuminosilicate, orsoda lime glass. In some embodiments, the article comprises a thin filmtransistor, photovoltaic device, diode, or display device.

In some embodiments, the article further comprises a functional layer onthe surface opposite of the organic semiconductor layer and dielectriclayer of the strengthened glass substrate, wherein the functional layeris selected from an anti-glare layer, an anti-smudge layer, aself-cleaning layer, an anti-reflection layer, an anti-fingerprintlayer, an optically scattering layer, anti-splintering, and combinationsthereof.

Another embodiment comprises a thin film transistor comprising: astrengthened glass substrate having a first surface and a second surfaceand having a Vickers crack initiation threshold of at least 7 kgf; anorganic semiconductor layer having a first surface and a second surface;a dielectric layer having a first surface and a second surface; and atleast one electrode; wherein the article does not contain a barrierlayer. In some embodiments, the at least one electrode comprises a gateelectrode, a drain electrode, and a source electrode. In someembodiments, the at least on electrode comprises a metal, conductingmetal oxide film, conducting metal nanoparticulate ink, or conductivepolymer. In some embodiments, the organic semiconductor layer comprisesa semiconducting small molecule, semiconducting oligomer, orsemiconducting polymer. In some embodiments, the dielectric layercomprises an organic or inorganic material that may be applied as a filmat a temperature less than about 250° C. In some embodiments, thestrengthened glass comprises an ion-exchanged glass.

In some embodiments, the thin film transistor further comprises afunctional layer on the surface opposite of the organic semiconductorlayer and dielectric layer of the strengthened glass substrate, whereinthe functional layer is selected from an anti-glare layer, ananti-smudge layer, a self-cleaning layer, an anti-reflection layer, ananti-fingerprint layer, an optically scattering layer, ananti-splintering layer, and combinations thereof.

In some embodiments, the thin film transistor comprises a bottom-gatetop-contact design. In some embodiments, the thin film transistorcomprises a bottom-gate bottom-contact design. In some embodiments, thethin film transistor comprises a top-gate top-contact design. In someembodiments, the thin film transistor comprises a top-gatebottom-contact design.

Another embodiment comprises a method of forming an article comprising:providing a strengthened glass substrate having a first surface and asecond surface and having a Vickers crack initiation threshold of atleast 7 kgf; providing an organic semiconductor layer; providing adielectric layer; and providing at least one electrode; wherein thearticle does not contain a barrier layer. In some embodiments, theproviding an organic semiconductor layer comprises coating thestrengthened glass substrate with the organic semiconductor layer andcoating the organic semiconductor layer with the dielectric layer. Insome embodiments, the providing a dielectric layer comprises coating thestrengthened glass substrate with the dielectric layer and coating thedielectric layer with the organic semiconductor layer.

In some embodiments, coating comprises spin casting, doctor blading,dip-coating, drop casting or various printing methods, such as ink jetprinting, slot die printing and gravure printing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view illustration of a bottom-gate top-contact (BG-TC)transistor based device wherein 38 is the drain electrode, 40 is thesource electrode, 32 is the gate electrode, 34 is the dielectric layer,10 is the ion-exchanged glass substrate, and 36 is the organicsemiconductor layer.

FIG. 2 is a side view illustration of a bottom-gate bottom-contact(BG-BC) transistor based device wherein 38 is the drain electrode, 40 isthe source electrode, 32 is the gate electrode, 34 is the dielectriclayer, 10 is the ion-exchanged glass substrate, and 36 is the organicsemiconductor layer.

FIG. 3 is a side view illustration of a top-gate bottom-contact (TG-BC)transistor based device wherein 38 is the drain electrode, 40 is thesource electrode, 32 is the gate electrode, 34 is the dielectric layer,10 is the ion-exchanged glass substrate, and 36 is the organicsemiconductor layer.

FIG. 4 is a side view illustration of a top-gate top-contact (TG-TC)transistor based device wherein 38 is the drain electrode, 40 is thesource electrode, 32 is the gate electrode, 34 is the dielectric layer,10 is the ion-exchanged glass substrate, and 36 is the organicsemiconductor layer.

FIG. 5 is a transfer curve of a fabricated BG-TC organic TFT comprisinga thiophene copolymerpoly[(3,7-diheptadecylthieno[3,2-b]thieno[2′,3′:4,5]thieno[2,3-d]thiophene-2,6-diyl)(2,2′-bithiophene-5,5′-diyl)](P2TDC17FT4) on a polymer dielectric layer. Based on the curve, it wasdetermined that the field-effect hole mobility of the device was 0.03cm²V·s, the on/off ration was 5×10³−1×10⁴, and the threshold voltage was−2.5 V.

FIG. 6 is a transfer curve of a TG-TC organic TFT comprisingpoly[(3,7-diheptadecylthieno[3,2-b]thieno[2′,3′:4,5]thieno[2,3-d]thiophene-2,6-diyl)(2,2′-bithiophene-5,5′-diyl)](P2TDC17FT4) organic semiconductor in contact with the ion exchangeglass substrate. The dielectric layer is a PVP-co-PMMA polymer. Themeasured transfer curve of the device reveals a field effect holemobility of 0.02 cm²/V·s, an on/off ratio of 700, and a thresholdvoltage of 5 V.

FIG. 7 shows the synthesis of two possible organic semiconductorpolymers that may be used in embodiments. FIG. 7A describes thesynthesis of a fused thiophene-iosindigo polymer and FIG. 7B describesthe synthesis of a stilbene-fused thiophene polymer.

FIG. 8 shows the synthesis of two possible organic semiconductorpolymers that may be used in embodiments. FIG. 8A describes thesynthesis of a fused thiophene-diketopyrrolopyrrole polymer and FIG. 8Bdescribes the synthesis of a bithiophene-fused thiophene polymer. WhereR=n-heptadecyl FIG. 8B shows the synthesis of P2TDC17FT4.

DETAILED DESCRIPTION

The present embodiments can be understood more readily by reference tothe following detailed description, drawings, examples, and claims, andtheir previous and following description. However, before the presentcompositions, articles, devices, and methods are disclosed anddescribed, it is to be understood that this description is not limitedto the specific compositions, articles, devices, and methods disclosedunless otherwise specified, as such can, of course, vary. It is also tobe understood that the terminology used herein is for the purpose ofdescribing particular aspects only and is not intended to be limiting.

The following description is provided as an enabling teaching. To thisend, those skilled in the relevant art will recognize and appreciatethat many changes can be made to the various embodiments describedherein, while still obtaining the beneficial results. It will also beapparent that some of the desired benefits can be obtained by selectingsome of the features without utilizing other features. Accordingly,those who work in the art will recognize that many modifications andadaptations to the present embodiments are possible and can even bedesirable in certain circumstances and are a part of the presentdescription. Thus, the following description is provided as illustrativeand should not be construed as limiting.

Disclosed are materials, compounds, compositions, and components thatcan be used for, can be used in conjunction with, can be used inpreparation for, or are embodiments of the disclosed method andcompositions. These and other materials are disclosed herein, and it isunderstood that when combinations, subsets, interactions, groups, etc.of these materials are disclosed that while specific reference of eachvarious individual and collective combinations and permutation of thesecompounds may not be explicitly disclosed, each is specificallycontemplated and described herein. Thus, if a class of substituents A,B, and C are disclosed as well as a class of substituents D, E, and F,and an example of a combination embodiment, A-D is disclosed, then eachis individually and collectively contemplated. Thus, in this example,each of the combinations A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F arespecifically contemplated and should be considered disclosed fromdisclosure of A, B, and C; D, E, and F; and the example combination A-D.Likewise, any subset or combination of these is also specificallycontemplated and disclosed. Thus, for example, the sub-group of A-E,B-F, and C-E are specifically contemplated and should be considereddisclosed from disclosure of A, B, and C; D, E, and F; and the examplecombination A-D. This concept applies to all aspects of this disclosureincluding, but not limited to any components of the compositions andsteps in methods of making and using the disclosed compositions. Thus,if there are a variety of additional steps that can be performed it isunderstood that each of these additional steps can be performed with anyspecific embodiment or combination of embodiments of the disclosedmethods, and that each such combination is specifically contemplated andshould be considered disclosed.

In this specification and in the claims which follow, reference will bemade to a number of terms which shall be defined to have the meaningsdetailed herein.

“Include,” “includes,” or like terms means encompassing but not limitedto, that is, inclusive and not exclusive.

The term “about” references all terms in the range unless otherwisestated. For example, about 1, 2, or 3 is equivalent to about 1, about 2,or about 3, and further comprises from about 1-3, from about 1-2, andfrom about 2-3. Specific and preferred values disclosed forcompositions, components, ingredients, additives, and like aspects, andranges thereof, are for illustration only; they do not exclude otherdefined values or other values within defined ranges. The compositionsand methods of the disclosure include those having any value or anycombination of the values, specific values, more specific values, andpreferred values described herein.

The indefinite article “a” or “an” and its corresponding definitearticle “the” as used herein means at least one, or one or more, unlessspecified otherwise

As used herein, the term “substrate” can be used to describe either asubstrate or a superstrate depending on the configuration of the device.For example, the substrate is a superstrate, if when assembled into, forexample, a photovoltaic cell, it is on the light incident side of aphotovoltaic cell. The superstrate can provide protection for thephotovoltaic materials from impact and environmental degradation whileallowing transmission of the appropriate wavelengths of the solarspectrum. Further, multiple photovoltaic cells can be arranged into aphotovoltaic module. Photovoltaic device can describe a cell, a module,or both.

As used herein, the term “adjacent” can be defined as being in closeproximity. Adjacent structures may or may not be in physical contactwith each other. Adjacent structures can have other layers and/orstructures disposed between them.

In a first aspect, embodiments comprise an article comprising: astrengthened glass substrate having a first surface and a second surfaceand having a Vickers crack initiation threshold of at least 7 kgf; anorganic semiconductor layer having a first surface and a second surface;a dielectric layer having a first surface and a second surface; and atleast one electrode; wherein the article does not contain a barrierlayer.

In some embodiments, the strengthened glass substrate comprises a glasssubstrate that has been mechanically, thermally, or chemically modifiedto increase the strength of the glass.

In one embodiment, the strengthened glass substrate is an ion-exchangedglass substrate. Ion-exchange is widely used to chemically strengthenglass articles for such applications. In this process, a glass articlecontaining a first metal ion (e.g., alkali cations in Li₂O, Na₂O, etc.)is at least partially immersed in or otherwise contacted with anion-exchange bath or medium containing a second metal ion that is eitherlarger or smaller than the first metal ion that is present in the glass.The first metal ions diffuse from the glass surface into theion-exchange bath/medium while the second metal ions from theion-exchange bath/medium replace the first metal ions in the glass to adepth of layer below the surface of the glass. The substitution oflarger ions for smaller ions in the glass creates a compressive stressat the glass surface, whereas substitution of smaller ions for largerions in the glass typically creates a tensile stress at the surface ofthe glass. In some embodiments, the first metal ion and second metal ionare monovalent alkali metal ions. However, other monovalent metal ionssuch as Ag⁺, Tl⁺, Cu⁺, and the like may also be used in the ion-exchangeprocess.

In one embodiment, the strengthened glass substrate comprises astrengthened glass wherein the glass is ion-exchanged to a depth oflayer of at least 20 μm from a surface of the glass. In anotherembodiment, the strengthened glass substrates described herein, whenchemically strengthened by ion-exchange, exhibit a Vickers initiationcracking threshold of at least about 5 kgf (kilogram force), in someembodiments, at least about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,17, 18, 19, or 20 kgf. In some embodiments, the strengthened glasssubstrates described herein, when chemically strengthened byion-exchange, exhibit a Vickers initiation cracking threshold of fromabout 5 kgf to about 50 kgf, about 5 kgf to about 40 kgf, about 5 kgf toabout 30 kgf, about 5 kgf to about 20 kgf, about 7 kgf to about 50 kgf,about 7 kgf to about 40 kgf, about 7 kgf to about 30 kgf, about 7 kgf toabout 20 kgf, about 10 kgf to about 50 kgf, about 10 kgf to about 40kgf, or about 10 kgf to about 30 kgf.

In some embodiments, the strengthened glass substrate comprises analkali containing glass. In some embodiments, the strengthened glasssubstrate comprises an aluminoborosilicate, analkalialuminoborosilicate, an aluminosilicate, an alkalialuminosilicate,or a soda lime glass. In some embodiments, the glass comprises an ionexchanged glass as described in U.S. Prov. Appl. Nos. 61/560,434,61/653,489, and 61/653,485, and U.S. application Ser. Nos. 12/858,490,12/277,573, 13/588,581, 11/888,213, 13/403,756, 12/392,577, 13/346,235,13/495,355, 12/858,490, 13/533,298, 13/291,533, and 13/305,271, all ofwhich are hereby incorporated by reference in their entirety.

According to some embodiments, the strengthened glass substrate has athickness of 4.0 mm or less, for example, 3.5 mm or less, for example,3.2 mm or less, for example, 3.0 mm or less, for example, 2.5 mm orless, for example, 2.0 mm or less, for example, 1.9 mm or less, forexample, 1.8 mm or less, for example, 1.5 mm or less, for example, 1.1mm or less, for example, about 0.05 mm to about 2.0 mm, for example,about 0.05 mm to about 1.1 mm, for example, about 0.1 mm to about 1.1mm. Although these are exemplary thicknesses, the strengthened glasssubstrate can have a thickness of any numerical value including decimalplaces in the range of from about 0.040 mm up to and including 4.0 mm.

In some embodiments, the organic semiconductor layer comprisessemiconducting small molecules, oligomers and/or polymers.Semiconducting small molecules include the polycyclic aromaticcompounds, such as pentacene, anthracene, and rubrene and otherconjugated aromatic hydrocarbons. Polymeric organic semiconductorsinclude, for example, poly(3-hexylthiophene), poly(p-phenylenevinylene), as well as polyacetylene and its derivatives. Generallyspeaking, there are two major overlapping classes of organicsemiconductors—organic charge-transfer complexes and variouslinear-backbone conductive polymers derived from polyacetylene andsimilar compounds, such as polypyrrole, and polyaniline. However,embodiments are not limited in scope to only these types of organicsemiconductors, and, as shown in the examples, are capable of workingwith a broad range of organic semiconductors.

In some embodiments, the organic semiconductor layer comprises a fusedthiophene compound. In some embodiments, the fused thiophene isincorporated into a polymer. Fused thiophenes and fused thiophenepolymers may comprise compounds as described in U.S. Pat. Nos.7,705,108, 7,838,623, 7,893,191, 7,919,634, 8,217,183, 8,278,346, U.S.application Ser. Nos. 12/905,667, 12/907,453, 12/935,426, 13/093,279,13/036,269, 13/660,637, 13/660,529, and U.S. Prov. Appl. Nos.61/617,202, and 61/693,448, all herein incorporated by reference intheir entireties.

Particular examples of fused thiophene compounds that may be usedinclude, but are not limited to,poly[(3,7-diheptadecylthieno[3,2-b]thieno[2′,3′:4,5]thieno[2,3-d]thiophene-2,6-diyl)(2,2′-bithiophene)-5,5′-diyl],poly[(3,7-diheptadecylthieno[3,2-b]thieno[2′,3′:4,5]thieno[2,3-d]thiophene-2,6-diyl)(2,5-dihexadecyl-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione)-5,5′-diyl],poly-3,6-dihexylthieno[3,2-b]thiophene (PDC6FT2),poly-3,6-didecanylthieno[3,2-b]thiophene,poly[(3,7-diheptadecylthieno[3.2-b]thieno[2′,3′:4,5]thieno[2,3-d]thiophene-2,6-diyl)(1-hexadecyl-3-(1-hexadecyl-2-oxoindol-3-ylidene)indol-2-one-6,6′-diyl)],andpoly[(3,7-diheptadecylthieno[3.2-b]thieno[2′,3′:4,5]thieno[2,3-d]thiophene-2,6-diyl)(stilbene-1,4′-diyl)].Additional examples of fused thiophene-based polymers are described inFIG. 7 and FIG. 8, wherein FIG. 7A shows a fused thiophene-iosindigopolymer and FIG. 7B describes a fused thiophene-stilbene polymer.Similarly, FIG. 8A shows a fused thiophene-diketopyrrolopyrrole polymerand FIG. 8B shows a bithiophene-fused thiophene polymer.

In some embodiments, the organic semiconductor layer may comprise one ormore electroluminescent organic compounds. In some embodiments, thesemiconducting small molecules, oligomers and/or polymers of thesemiconductor layer may comprise electroluminescent organic compounds.

In some embodiments, the organic semiconductor layer is formed by suchprocesses as dip coating, spin coating, Langmuir-Blodgett deposition,electrospray ionization, direct nanoparticle deposition, vapordeposition, chemical deposition, spray deposition, screen printing,nano-imprint lithography, gravure printing, doctor blading,spray-coating, slot die coating, ink jet printing, laser deposition,drop casting or chemical etching.

In some embodiments, the dielectric layer comprises any organic orinorganic material that is able to be applied as a film at or below 200°C. Examples of dielectrics that may be used in embodiments includepolymers, glasses, and inorganic or organic materials. The dielectriclayer may be formed by, for example, such processes as sputter coating,atomic layer deposition, dip coating, spin coating, Langmuir-Blodgettdeposition, electrospray ionization, direct nanoparticle deposition,vapor deposition, chemical deposition, vacuum filtration, flame spray,electrospray, spray deposition, electrodeposition, screen printing,close space sublimation, nano-imprint lithography, in situ growth,microwave assisted chemical vapor deposition, laser ablation, arcdischarge, gravure printing, doctor blading, spray-coating, slot diecoating, or chemical etching.

In some embodiments, the electrode comprises gate, drain, and sourceelectrodes. Electrodes can comprise any conducting material—includingfor example, metals, conducting semi-metals, or conducting non-metals.For example, in some embodiments, an electrode may comprise a metal orcombination of metals in the form of a coating, wire, sheet, ribbon,micro- or nanoparticle, or mesh. Electrodes may be formed via suchprocesses as sputter coating, atomic layer deposition, dip coating, spincoating, Langmuir-Blodgett deposition, electrospray ionization, directnanoparticle deposition, vapor deposition, chemical deposition, vacuumfiltration, flame spray, electrospray, spray deposition,electrodeposition, screen printing, close space sublimation,nano-imprint lithography, in situ growth, microwave assisted chemicalvapor deposition, laser ablation, arc discharge, gravure printing,doctor blading, spray-coating, slot die coating, or chemical etching.

Embodiments do not include a barrier layer. As used herein, a barrierlayer consists of a material positioned between the strengthened glasssubstrate and the organic semiconductor layer or the source electrodethat prevents ion migration. In some embodiments, for example BG-TC andBG-BC type transistors, there may exist a dielectric layer between theorganic semiconductor layer and the ion exchanged glass substrate, butno barrier layer between the gate electrode and the ion exchanged glasssubstrate. In some embodiments, for example TG-TC and TG-BC typetransistors, there is no barrier layer or dielectric layer between theorganic semiconductor layer and the ion exchanged glass substrate.Traditionally, aluminum oxide and silicon nitride have been used asbarrier layers in thin film transistors and other electronic devices.

In some embodiments, the article further comprises an anti-glare layer,an anti-smudge layer, a self-cleaning layer, an anti-reflection layer,an anti-fingerprint layer, an optically scattering layer, ananti-splintering layer, and combinations thereof. Such layers may beincorporated through any number of known processes, such as thosedisclosed in U.S. Patent Publ. Nos. 2011/0129665, 2009/0197048,2009/0002821, 2011/0267697, 2011/0017287, or 2011/0240064, hereinincorporated by reference.

In another aspect, an embodiment of an article is an organic thin filmtransistor. An organic TFT device can include: an ion-exchanged glasssubstrate including the barrier layer. On the barrier layer a gateelectrode, a dielectric layer, a drain electrode, a source electrode,and an organic semiconducting channel layer can be formed. These layerscan be stacked in different sequences to form a laterally or verticallyconfigured transistor device. The organic semiconducting channel layerincludes semiconducting small molecules, oligomers and/or polymers. Thedielectric layer can be composed of any organic or inorganic materialthat is able to be applied as a film at or below 200° C. In this way, amechanically durable backplane is produced.

FIGS. 1-4 illustrate embodiments of articles comprising TFT devices. Asused herein, the term “bottom-gate top-contact transistor” refers to aTFT device comprising an exemplary structure as shown in FIG. 1. A gateelectrode 32 is deposited on a strengthened glass substrate, orion-exchanged glass substrate 10 (according to any of the previouslydescribed embodiments) followed by a dielectric layer 34 and then asemiconducting layer 36. Drain and source electrodes 38 and 40,respectively, are further deposited on top of the semiconducting layer36.

The term “bottom-gate bottom-contact transistor” refers to a TFT devicecomprising an exemplary structure as shown in FIG. 2. A gate electrode32 is deposited on a strengthened glass substrate, or ion-exchangedglass substrate 10 followed by a dielectric layer 34 and then drain andsource electrodes 38 and 40, respectively. A semiconducting layer 36 isfurther deposited on top of these underlying layers.

The term “top-gate bottom-contact transistor” refers to a TFT devicecomprising an exemplary structure as shown in FIG. 3. Drain and sourceelectrodes 38 and 40, respectively are deposited on a strengthened glassor ion-exchanged glass substrate 10 (according to any of the previouslydescribed embodiments). A semiconducting layer 36 is then deposited ontop, followed by a dielectric layer 34 and then a gate electrode 32.

The term “top-gate top-contact transistor” refers to a TFT devicecomprising an exemplary structure as shown in FIG. 6. A semiconductinglayer 36 is deposited on a strengthened glass substrate, orion-exchanged glass substrate 10 followed by drain and source electrodes38 and 40, respectively. A dielectric layer 34 is further deposited ontop, followed by a gate electrode 32.

Another aspect comprises methods of forming embodiments, comprising:providing a strengthened glass substrate having a first surface and asecond surface and having a Vickers crack initiation threshold of atleast 20 kgf; providing an organic semiconductor layer; providing adielectric layer; and providing at least one electrode; wherein thearticle does not contain a barrier layer. As noted above, it is possiblevia a number of processes, all incorporated herein, to provide thevarious elements described. In some embodiments, providing an organicsemiconductor layer comprises coating the strengthened glass substratewith the organic semiconductor layer and coating the organicsemiconductor layer with the dielectric layer. In some embodiments,providing a dielectric layer comprises coating the strengthened glasssubstrate with the dielectric layer and coating the dielectric layerwith the organic semiconductor layer.

EXAMPLES Example 1 Organic Bottom-Gate, Top-Contact Thin FilmTransistors on Ion Exchange Glass

Ion exchanged glass substrates were cleaned by using sonication inacetone and then isopropanol. The 30 nm thick Au gate electrode wasdeposited on the substrate by thermal evaporation of Au at 2 Å/s. Thedielectric comprised a mixture of 11 wt % (film thickness approximately800 nm-1 μm) PVP solution in PGMEA and melamine, which was spin-castonto the substrate at 1000 rpm for 30 seconds. This dielectric was curedvia UV irradiation for approximately 3 minutes. Then, 3 mg/mL of asemiconducting polymerPoly[(3,7-diheptadecylthieno[3,2-b]thieno[2,3′:4,5]thieno[2,3-d]thiophene-2,6-diyl)(2,2′-bithiophene)-5,5′-diyl](P2TDC17FT4) dissolved in 1,2-dichlorobenzene was spin-coated onto thesubstrate. The device was annealed at 100° C. for 30 minutes on ahotplate. Finally, 30 nm thick Au source and drain electrodes weredeposited by thermal evaporation of Au at 2 Å/s. The transfer curve(FIG. 5) of fabricated organic TFT device reveals a field-effect holemobility of 0.03 cm²/V·s, an on/off ratio of 5×10³-1×10⁴, and athreshold voltage of −2.5 V.

Example 2 Organic Top-Gate, Top-Contact Thin Film Transistors on IonExchange Glass

Ion exchanged glass was cleaned by deionized water, followed bysonication in toluene, and then acetone, and 2-propanol. Glasssubstrates were then placed in a UV-Ozone cleaner for 10 mins andsubsequently exposed to a surface treatment of octyltrichlorosilanevapor for 30 minutes. The organic semiconductorPoly[(3,7-diheptadecylthieno[3,2-b]thieno[2′,3′:4,5]thieno[2,3-d]thiophene-2,6-diyl)(2,5-dihexadecyl-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione)-5,5′-diyl](PTDC16DPPTDC17FT4) was spin cast onto the cleaned substrates at 1000rpm for 60 seconds, then annealed at 130° C. on a hotplate forapproximately 30 minutes. After annealing, 30 nm thick Au source anddrain electrodes were deposited by thermal evaporation of Au at a rateof 2.5 Å/s. Next, 2 ml of 5 wt % PVP-co-PMMA with melamine (weight ratioof PVP-co-PMMA: melamine=10:1) solution in PGMEA solvent was spin castonto the substrate at 1000 rpm for 60 seconds, placed on a hotplate at120° C. for 2 minutes to remove solvent, and cured under UV light tocross-link the dielectric film 50 nm Au gate electrodes were thenthermally deposited at 2.5 Å/s. The measured transfer curve of thedevice (FIG. 6) reveals a field-effect hole mobility of 0.02 cm²/V·s, anon/off ratio of 700, and a threshold voltage of −5 V.

We claim:
 1. An article comprising: a. a strengthened glass substratehaving a first surface and a second surface and having a Vickers crackinitiation threshold of at least 20 7 kgf; b. an organic semiconductorlayer having a first surface and a second surface, wherein the firstsurface of the organic semiconductor layer is in direct contact with thesecond surface of the strengthened glass substrate; c. a dielectriclayer having a first surface and a second surface; and d. at least oneadditional electrode; wherein the article does not contain a barrierlayer between the organic semiconductor layer and the strengthened glasssubstrate; wherein the strengthened glass comprises an ion-exchangedglass; and wherein the article comprises a top-gate thin filmtransistor, photovoltaic device, diode, or display device.
 2. Thearticle of claim 1, wherein said at least one electrode comprises a gateelectrode, drain electrode, or a source electrode.
 3. The article ofclaim 1, wherein the at least one electrode comprises a metal,conducting metal oxide film, conducting metal nanoparticulate ink, orconductive polymer.
 4. The article of claim 1, wherein the organicsemiconductor layer comprises a semiconducting small molecule,semiconducting oligomer, or semiconducting polymer.
 5. The article ofclaim 4, wherein the semiconducting small molecule, semiconductingoligomer, or semiconducting polymer comprises a fused thiophene moiety.6. The article of claim 1, wherein the dielectric layer comprises anorganic or inorganic material that may be applied as a film at atemperature less than about 250° C.
 7. The article of claim 1, furthercomprising a functional layer on the surface opposite of the organicsemiconductor layer and dielectric layer of the strengthened glasssubstrate, wherein the functional layer is selected from an anti-glarelayer, an anti-smudge layer, a self-cleaning layer, an anti-reflectionlayer, an anti-fingerprint layer, an optically scattering layer, ananti-splintering layer, and combinations thereof.
 8. The article ofclaim 1, wherein the article comprises a top-gate top-contact ortop-gate bottom-contact thin film transistor.
 9. An article comprising:a. a strengthened glass substrate having a first surface and a secondsurface and having a Vickers crack initiation threshold of at least 20 7kgf; b. an organic semiconductor layer having a first surface and asecond surface; c. a dielectric layer having a first surface and asecond surface wherein the first surface of the dielectric layer is indirect contact with the organic semiconductor layer; d. a gate electrodein direct contact with the strengthened glass substrate and the secondsurface of the dielectric layer; and e. at least one additionalelectrode; wherein the article does not contain a barrier layer betweenthe gate electrode and the strengthened glass substrate wherein thestrengthened glass comprises an ion-exchanged glass; and wherein thearticle comprises a bottom-gate thin film transistor, photovoltaicdevice, diode, or display device.
 10. The article of claim 9, whereinsaid at least one electrode comprises a drain electrode or a sourceelectrode.
 11. The article of claim 9, wherein the at least oneelectrode comprises a metal, conducting metal oxide film, conductingmetal nanoparticulate ink, or conductive polymer.
 12. The article ofclaim 9, wherein the organic semiconductor layer comprises asemiconducting small molecule, semiconducting oligomer, orsemiconducting polymer.
 13. The article of claim 12, wherein thesemiconducting small molecule, semiconducting oligomer, orsemiconducting polymer comprises a fused thiophene moiety.
 14. Thearticle of claim 9, wherein the dielectric layer comprises an organic orinorganic material that may be applied as a film at a temperature lessthan about 250° C.
 15. The article of claim 9, further comprising afunctional layer on the surface opposite of the organic semiconductorlayer and dielectric layer of the strengthened glass substrate, whereinthe functional layer is selected from an anti-glare layer, ananti-smudge layer, a self-cleaning layer, an anti-reflection layer, ananti-fingerprint layer, an optically scattering layer, ananti-splintering layer, and combinations thereof.
 16. The article ofclaim 9, wherein the article comprises a bottom-gate top-contact orbottom-gate bottom-contact thin film transistor.
 17. A method of formingthe article of claim 1, comprising: a. providing a strengthened glasssubstrate having a first surface and a second surface and having aVickers crack initiation threshold of at least 20 7 kgf; b. providing anorganic semiconductor layer; c. providing a dielectric layer; and d.providing at least one electrode; wherein the article does not contain abarrier layer.
 18. The method of claim 17, wherein the providing anorganic semiconductor layer comprises coating the strengthened glasssubstrate with the organic semiconductor layer and coating the organicsemiconductor layer with the dielectric layer.
 19. The method of claim17, wherein the providing a dielectric layer step comprises coating thestrengthened glass substrate with the dielectric layer and coating thedielectric layer with the organic semiconductor layer.
 20. The method ofclaim 19, wherein coating comprises sputter coating, atomic layerdeposition, ink jet printing, slot-die printing, dip coating, spincoating, Langmuir-Blodgett deposition, electrospray ionization, directnanoparticle deposition, vapor deposition, chemical deposition, vacuumfiltration, flame spray, electrospray, spray deposition,electrodeposition, screen printing, close space sublimation,nano-imprint lithography, in situ growth, microwave assisted chemicalvapor deposition, laser ablation, arc discharge, gravure printing,doctor blading, spray-coating, slot die coating, or chemical etching.21. A method of forming the article of claim 9, comprising: a. providinga strengthened glass substrate having a first surface and a secondsurface and having a Vickers crack initiation threshold of at least 20 7kgf; b. providing an organic semiconductor layer; c. providing adielectric layer; and d. providing a gate electrode in contact with thestrengthened glass substrate and the dielectric layer e. providing atleast one additional electrode; wherein the article does not contain abarrier layer between the gate electrode and the strengthened glasssubstrate.
 22. The method of claim 21 17, wherein the providing anorganic semiconductor layer comprises coating the strengthened glasssubstrate with the organic semiconductor layer and coating the organicsemiconductor layer with the dielectric layer.
 23. The method of claim21, wherein the providing a dielectric layer comprises coating thestrengthened glass substrate with the dielectric layer and coating thedielectric layer with the organic semiconductor layer.
 24. The method ofclaim 23, wherein coating comprises sputter coating, atomic layerdeposition, ink jet printing, slot-die printing, dip coating, spincoating, Langmuir-Blodgett deposition, electrospray ionization, directnanoparticle deposition, vapor deposition, chemical deposition, vacuumfiltration, flame spray, electrospray, spray deposition,electrodeposition, screen printing, close space sublimation,nano-imprint lithography, in situ growth, microwave assisted chemicalvapor deposition, laser ablation, arc discharge, gravure printing,doctor blading, spray-coating, slot die coating, or chemical etching.